Composite textile yarn



United States atent O 3,543,504 COMPOSITE TEXTILE YARN Ronald S. Goy, Sutton Coldfield, England, assignor to The Dunlop Company Limited, London, England, a British company No Drawing. Filed Aug. 14, 1968, Ser. No. 752,480 Claims priority, application Great Britain, Aug. 25, 1967, 39,139/ 67 Int. Cl. D02g 3/02 US. Cl. 57-157 16 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a method of making improved textile yarns.

According to the present invention, a method of making a textile yarn comprises twisting together at least one filament of paper and at least one filament of a manmade textile material and subjecting the twisted filaments under tension to a heat-setting operation.

According to the present invention also, there is provided a textile yarn when mad by the method described in the immediately preceding paragraph.

The filaments of paper and textile material may be in the form of flat strips made, e.g., by slitting a wide sheet, or may be in the form of one or more monofilaments or cords having a substantially circular cross-section, and the textile yarn may include a combination of various types of filament, if desired. Preferably, both the paper and the textile material are in the form of flat strips. The use of the term strip herein is' intended to encompass both flat and circular or part-circular cross sections. The dimensions of the filaments employed will depend on the desired dimensions and properties of the textil yarn, and filaments in textile yarns to be used in carpet manufacture may suitably be flat strips having a width of from 0.1 to 0.25 inch and a thickness of up to 0.005 inch.

The proportions of paper and textile material in the yarn depend on the properties desired. Generally, the textile material is employed to give strength to the yarn and the paper is employed to give bulk and resistance to heat-shrinkage to the yarn. Yarns suitable for carpet manufacture may contain from 40 to 90 weight percent of paper.

The man-made textile material may be, for example, a rayon or a thermoplastic polymer, e.g. polypropylene, polyethylene, a nylon or a polyester, e.g. poly(ethylene terephthalate). If desired, the textile material filament may be a laminate strip of two or more polymers and in this case the polymers should have similar melting points, e.g. polypropylene/ polyethylene or nylon/polyester laminates. The textile material filaments used to make the yarn may be crimped and/or fibrillatable and may or may not be fibrillated during manufacture of the yarn.

Each filament of textile material is normally in a drawn state to give it orientation and preferably the filament is fully drawn to its natural draw ratio prior to twisting it with the paper. The filaments of textile material and paper may, if desired, be twisted individually before they are twisted together. The twisting may be acice complished on conventional doubling equipment, e.g. a ring-twister, and when untwisted filaments are twisted together it is preferred to withdraw the filaments over the side of their packages to keep them flat and to feed them on top of each other into the feed-roller system.

The paper may be any paper that is strong enough and flexible enough to be made into yarns and an especially suitable type of paper is a kraft paper. If desired, the paper may be treated prior to forming it into filaments or twisting with the textile material filaments, and examples of such pretreatment are dyeing, impregnating with a resin, and coating with polyethylene. Also, the paper filaments may be crimped in order to assist the paper to stretch during any subsequent manipulation of the filaments.

Crimped paper filaments may generally be twisted dry but in many cases the paper filaments, crimped or not, are preferably moistened before they are twisted in order to make them more flexible and less liable to rupture. Moistening of the filaments may be achieved by passing them through a water-bath or bringing them into contact with a wet roller. If desired, the water with which the paper is moistened may contain one or more additives to confer desired properties on the paper, for example, the paper may be given improved strength, given improved moisture-resistance, dyed or glue-sized by means of appropriate additives.

The amount of twist which may be applied to the individual filaments and the amounts of twist applied to the yarn depends on the denier of the filaments. Generally, the amount of twist applied to a filament of yarn should be within the range of twist factors 3.95 to 49.3 where twist factor is defined as the number of turns per centimetre times the square root of the count in tex (Textile Terms & Definitions, 1963, Butterworths). The unit tex is the weight in grammes per 1000 metres of filament or yarn. Suitably, when untwisted filaments are twisted together, the amount of twist in the yarn may be from 0.2 to 2.5 turns/cm. for a yarn of about 390 tex.

The yarn produced by merely twisting filaments together generally has a comparatively uneven surface and when subjected to high strain the component filaments tend to break at their normal, individual maximum extensibilities. Although such yarns may 'be suitable for some applications in which yarn strength is not a major factor, it is desirable for many purposes to utilise a yarn which has a smooth surface and a uniform breaking strength and extensibility. It is found that this may be achieved by subjecting the yarn to a heat-setting operation whilst the yarn is under tension. The term heat-setting means the stabilization of the yarn against shrinkage during subsequent processing, by heating the yarn.

The temperature and time of heat-setting will depend on the particular filaments employed. When the manmade textile material in the yarn is a thermoplastic material, suitable heat-setting temperatures are within 50 C., and preferably within 20 C., of the melting point of the textile material for a time of a few seconds. When the man-made textile material in the yarn is a nonthermoplastic material such as rayon the heat-setting temperature may be just sufficient to drive off the moisture and achieve consolidation, e.g. just above 0; however, such material may be heat-set at a higher temperature for a shorter time, if desired, eg a yarn of 390 tex comprising rayon as the textile material may be heat-set at 250 C. for 4 seconds.

When a yarn comprises a thermoplastic material as the textile material, the yarn may suitably be stretched by up to 20 percent and usually by about 4 to 5 percent during the heat-setting operation. If desired, the yarn may be heat-set under controlled conditions of relaxation as described in co-pending US. patent application 720/38, filed Apr. 10, 1968 in which there is described a method wherein a yarn is consecutively stretched and relaxed whilst being heated at the heat-setting temperature. Also, if desired, the yarn may be given twist during the heatsetting operation.

The heating means employed in the heat-setting operation may be any suitable means such as a hot-plate, a hot liquid or an air-oven, but preferably the means is a heated bed of fluidised solid particles, e.g. sand or glass particles.

The paper in the yarn should contain some moisture in order to enable it to be heat-set without breaking. The moisture content may generally be from to 75 percent by weight based on the dry weight of the paper and in order to achieve this it is usually necessary to wet the paper in order to supplement its normal moisture content, for example, by passing the yarn through a water bath or bringing it into contact with a wet roller. Here again, the water may contain additives, e.g. a dye, glue or resin, to confer desired properties on the yarn. A preferred moisture content of the paper for the purposes of the heat-setting operation is about 50 percent by weight based on the dry weight of the paper.

If the paper in the yarn has a polyethylene coating, this may suitably be caused to melt during the heatsetting operation so that it flows and penetrates the yarn and thereby bestows water-resistance on the yarn. This is especially desirable when the yarn is to be used in carpet manufacture since the carpet may then be safetly wet-cleaned in situ.

When it is desired to adhere the yarn to a rubber composition the yarn may be provided with a coating of an adhesive composition, e.g. a resorcinol-formaldehyderubber latex composition. Such a coating may, if desired, be applied by passing the yarn through a 'bath of the composition instead of or in addition to passing it through a water bath or in contact with a wet roller immediately prior to the heat-setting operation.

The yarns of this invention may be used to reinforce rubber and plastics compositions, e.g. poly(vinyl chloride) compositions, for instance in conveyor belting, V belts, floor tiles and hose, but they are especially suitable for use in carpet backings.

The material conventionally used in carpet backings, namely jute, has the desired bulk but it suffers from a number of disadvantages, e.g. (a) it is liable to break during weaving and thereby cause the formation of a smile on the carpet surface, (b) it produces flights during weaving and these settle on the loom and contaminate the pile, (c) it absorbs back-size and latex, (d) it is subject to rotting, wet-shrinkage, attack by moths and staining, and (e) it does not have the most desirable abrasion-resistance and modulus. The yarns of the present invention do not have these disadvantages and they may advantageously be used as the sole carpet backing yarn or they may be used in addition to jute and or other yarn. Moreover, the yarns of this invention are advantageous over yarns consisting entirely of paper in that paper filaments are ditficult to manipulate and usually need to be wet-twisted, and paper yarns which are strong enough for carpet manufacture have a low rupture point and, thus, are difficult to process unless given special handling treatment. Also, the yarns of this invention are advantageous over yarns consisting entirely of a man-made textile material by having a desirably high bulk, a good resistance to heat-shrinkage and an easy adhesion to rubber and plastics compositions whilst maintaining a good extensibility and breaking strength.

The invention is illustrated in the following example:

EXAMPLE A fully drawn polypropylene fibrillatable tape 0.12 inch wide by 0.002 inch thick was twisted with a kraft paper strip 0.15 inch wide by 0.002 inch thick to a total of 0.9 turn per cm. The combined yarn was wetted by passing it through a water bath and then stretched by 5 percent at 240 C. for 6 seconds in a fluidised bed of solid glass particles of about 0.25 mm. diameter obtainable commercially under the trade name Ballotini.

The yarn properties were:

Breaking load (kg.) 7.6 Extension at break (percent) 8.6 Tenacity (gm./tex) 20.7 Adhesion to rubber (kg.) 1.5

A similar yarn subsequently treated with a resorcinolformaldehyde-rubber latex composition had the following properties:

Breaking load (kg) Extension at break (percent) 8.8 Tenacity (gm./tex) 18.9 Adhesion to rubber (kg) 2.5

The adhesion to rubber is the force required to pull cm. of the yarn from a block of a natural rubber composition which had been vulcanized in contact with the yarn at 153 C. for 30 minutes. The rubber composition had the formulation:

Part(s) by wt.

Natural rubber 100.0 GPF carbon black 45.0 Pine tar 4.0 Process oil 6.0 Stearic acid 1.0 Zinc oxide 6.0 Nitroso-diphenylamine 0.5 Sulphur 2.6 2-(4-morpholine mercapto)-'benzthiazole 0.7

Having now described my invention, what I claim is:

1. A method of making a textile yarn which comprises twisting together at least one strip of paper and at least one filament of a man-made textile material, applying tension to the twisted strip and filament, and subjecting the twisted strip and filament to a heat-setting operation.

2. A method according to claim 1 in which said at least one strip is in the form of a flat strip.

3. A method according to claim 2 in which said at least one strip has a width of from 0.1 to 0.25 inch and a thickness of up to 0.005 inch.

4. A method according to claim 1 in which the amount of paper in the yarn is from 40 to by weight.

5. A method according to claim 1 in which the manmade textile material is a thermoplastic polymer.

6. A method according to claim 5 in which the thermoplastic polymer is polypropylene.

7. A method according to claim 5 in which the heatsetting temperature is within 50 C. of the melting point of the material.

8. A method according to claim 5 in which the heatsetting temperature is within 20 C. of the melting point of the material.

9. A method according to claim 5 including stretching the yarn up to 20% during the heat-setting operation.

10. A method according to claim 5 including stretching the yarn 4 to 5% during the heat-setting operation.

11. A method according to claim 1 in which the strip of paper is twisted with a man-made textile material filament being a laminate of two or more polymer strips having similar melting points.

12. A method according to claim 1 including drawing the textile material to its natural draw ratio prior to twisting with the paper.

13. A method according to claim 1 in which the paper is a kraft paper.

14. A method according to claim 1 in which said at least one strip is twisted within the range of twist factors 3.95 to 49.3.

15. A method according to claim 1, wherein the yarn 2,918,784 12/1959 Faircloth 57167 is subjected to said heat setting operation by heating 2,981,052 4/1961 MacHenry 57150 XR said yarn in a bed of fluidized solid particles. 3,035,405 5/ 1962 Welsh 57-165 16. A method according to claim 1 in which the paper 3,349,552 10/1967 Port et a1 57167 XR has a polyethylene coating which is melted during the 5 3,357,172 12/1967 Evans 57167 XR heat-setting operation. 3,398,220 8/1968 Port et al. 57167 XR References Cited STANLEY N. GILREATH, Primary Examiner UNITED STATES PATENTS W. H. SCHROEDER, Assistant Examiner 2,336,100 12/1943 Jacque 57-167 10 2,482,895 9/1949 Brockman et a1. 57--165 2,871,652 2/1959 Schwartz 57167 XR 57140 

